1. Field of the Invention
The present invention relates to an antinoise device for impact serial printers used in data processing systems.
2. Description of the Prior Art
It is known that one of the main inconveniences of the impact printers is the considerable noise generated during their working. This is one of the reasons which have led the manufacturers to invest in the research and development of non-impact printers which are intrinsically noiseless (e.g. ink jet, electrostatic and so on). However, the need to have several printed copies existing in several administrative activities still requires the use of impact printers; moreover, the printing speed of impact printers of matrix type satisfies, at present, the need of a large range of users.
In the prior art, the solutions adopted to reduce the noise of such printers were to equip them with covers and frames internally lined with deadening material and enclosing the noise source in the best possible way. The purpose, however, was to reduce the effects not to remedy the causes, since the noise causes were considered impossible to be eliminated or reduced.
It is known that an impact serial printer generally comprises a rigid frame equipped with parallel guides arranged in the direction of the printing line and a platen on which a printing support is leaned. Guides and platen are strictly fixed to the frame and are part of the same. A printing carriage equipped with a printing head, (such as a needle head), which slides on guides for mosaic printing or font bearing element for solid font printing.
It has been experimentally noted that the main noise source is given by the impact of the platen caused by the printing head and by the vibrations of the printing support (paper), which acts as a vibrating membrane caused by the printing operations. What is required is to eliminate the causes of the noise rather than the effects.